Trinuclear methine dyes for use in electrophotographic systems

ABSTRACT

Trinuclear methine dyes and intermediates therefor, prepared by quaternizing oxonols, converting the quaternary compound to an inner anhydride, and condensing the latter with a heterocyclic compound having a reactive methyl or methylene group to yield a trinuclear methine dye; and use of the resulting dye to sensitize photoconductive zinc oxide for electrophotography.

United States Patent Yao 1 1 Oct. 1, 1974 [541 TRINUCLEAR METHINE DYES FOR USE IN 3.047.384 7/1962 Jones ct 111. 96 17 ELECTROPHOTOGRAPHIC SYSTEMS 3,507,649 4/1970 Hensley 260/240.4 X 3,576,639 4/1971 Jenkins 96/127 Inventor: Shi-Kuang Y ng t n, v 3.628951 12/1971 Yao 96 17 [73] Assignee: GAF Corporation, New York, NY. 7 [22] Fil d; M 3, 1971 Primary ExaminerJohn D. Randolph A: -W pp NO: 120,751 Letgirfy, Agent, or Fzrm alter C Kehm, Samson B Related US. Application Data [62] Division of Ser. No. 717,986, April 1, 1968, Pat. No.

[57] ABSTRACT U-S. a .6, Trinuclear methine dyes and intermediates therefor 2510/2401, 260/298 prepared by quaternizing oxonols, converting the qua- 260/304, 260/307 D, 260/309.2, 260/326.13 ternary compound to an inner anhydride, and con- R densing the latter with a heterocyclic compound hav- [51] Int. Cl C09b 23/10 ing a reactive methyl or methylene group to yield a m- [58] Field of Search 260/240.1, 240.2, 240.4 nuclear methine and use f the resulting dye to sensitize photoconductive zinc oxide for electropho- [56] References Clted tography UNITED STATES PATENTS 2,535,994 12/1950 Thompson 260/240.l 1 Claim, N0 Drawings TRINUCLEAR METHINE DYES FOR USE IN ELECTROPHOTOGRAPHIC SYSTEMS This application is a divisional of US. Pat. application Ser. No. 717,986 filed Apr. 1, 1968 and now patented as U.S. Pat. No. 3,628,951.

This invention relates to novel trinuclear methine dyes, intermediates therefor,a process for their preparation, and their use in sensitizing zinc oxide as a photoconductor in electrophotographic materials.

It was known heretofore that reactive derivatives of 3-alkylrhodanines, substituted in 5-position, by acetanilinomethylene-, anilinomethyleneor ethoxymethylen-radicals (U.S. Pat. Nos. 2,494,031, 2,658,890) could be used as starting materials for preparation of complex salts of bis-rhodanine-methine or oxonol dyes. Moreover, bis-rhodanine-methine dyes have been prepared from 3-alkylrhodanines by reaction with ethylorthoformate or diethoxymethylacetate (U.S. Pat. No. 2,533,206) in a basic condensation medium. Thus, preparation of oxonol or bis-rhodaninemethine dyes is well known in the art.

It is an object of this invention to provide a novel method for preparing quaternary anhydro inner salts from oxonols and to prepare novel trinuclear dyes from the resulting inner salts, as well asto incorporate said dyestuffs as sensitizers for photoconductive zinc oxide in electrophotographic coatings.

In accordance with this invention, an oxonol dye is converted to a quaternary salt, and the latter hydrolyzed to an anhydro inner salt by purification in a polar solvent. The resulting quaternary anhydro inner salt is then condensed with a N-heterocyclic compound having a reactive methylor methylene group to form a novel class of trinuclear methine dyes. The latter are incorporated as sensitizers in photoconductive zinc oxide coatings foruse in electrophotographic materials.

More particularly, in accordance with this invention, an oxonol corresponding to one of the following formulas:

atoms in the heterocyclic ring, as for example, a rhodanine nucleus, a thiazole-2,4-dione nucleus, a 2- thiooxazolidone nucleus or the like, is treated with a quaternizing reagent such as dimethyl sulfate or methyl or ethyl paratoluene sulfonate. The resulting quaternized complex salt is purified by heating in a polar solvent-especially a lower alcohol such as methyl, ethyl or isopropyl alcohol, preferably diluted to about 50 percent concentration with water. The quaternary compound is hydrolyzed by this treatment to a quaternary anhydro inner salt which separates from the solvent-the salts resulting from the compounds corresponding to the formulas above indicated having the following formulas respectively:

and

bit-Z RIAnion- 4 wherein R represents a lower alkyl or lower carboxyalkyl group, and X represents the non-metallic atoms necessary to complete a heterocyclic nucleus having five to six carbon atoms in the heterocyclic ring. The resulting trinuclear dyes correspond to the general formulas:

wherein Q represents one of the radicals:

and

wherein R, R,, R R.,, A, X, Y and Z have the same significance as indicated hereinabove.

EXAMPLE 1 6.5 grams of the complex inner salt of bis-[-(3- ethylrhodanine)-methine cyanine] were preheated with 30 ml. of purified chlorobenzene on a constant temperature bath at 131 C. for minutes. 30 ml; of purified dimethyl sulfate were added, and heating continued for 5 minutes at the same temperature. Upon cooling, the mixture was treated three times with ethyl ether. The oily residue was then boiled with 18 ml. isopropanol and then diluted with 18 ml. of water. Upon cooling, the quaternary inner anhydro salt separated in the form of a reddish-brown solid having a melting point of 236 237 C. Upon analysis, it was found to correspond to the empirical formula C H, N O S the yield being 4.61 g. corresponding to 93.1 percent of theory. Its formula is as follows:

EXAMPLE 2 18.54 g. of the aforesaid anhydro inner salt of Example l were added, together with 20.2 g. of 3- carboxyethyl-6-methoxy-2-methyl-benzothiazolium iodide, to 150 ml. of isopropanol. After mixing thoroughly, 34.28 ml. of triethylamine were added. After stirring for 2 minutes, the mixture was heated to boiling for three minutes, and then diluted with three times its volume of water. After neutralizing with 37.7 ml. of glacial acetic acid, the mixture was cooled in ice water for 20 minutes. The dyestuff which separated from the solution was recovered by filtration and boiled three times with methanol. 18.02 g. (59.7 percent of theory) of dyestuff was obtained in the form of greenish crystals melting at 240 241 C. with decomposition. On analysis, it was found to correspond to the empirical formula C H N O S CH OH. lts formula is as follows:

H COOH A series of examples were carried out utilizing the procedure of Example 1, but substituting for the oxonol intermediate, a molecularly equivalent amount of an oxonol intermediate corresponding to the formula:

which yielded a series of anhydro inner salts corresponding to the formula:

wherein Y, R and R, correspond to the moieties indicated in the following table:

In addition, the same procedure was employed to. convert the oxonol intermediates shown in Examples 10 and 11 to their quaternary anhydro inner salts, the reactions being represented as follows:

EGHB i s EXAMPLE 1.1 I I wherein?i'rnsfiafignsve he significanceindicated in thefollowing table; s /(ll,=CH-.-C-Z ES r g .TABLE 3 2H5 N 5 ..-l.

4351; Ex mple No- Y R R. R

25 S eth l eth l curb m th 1 26 S ethg' l ethzl car rl ye t hyl N Or $286311; 27 S ethyl ethyl ethyl lo 28 S ethyl carboxyethyl carboxyethyl 4E5 .4

5436 Pr para on o tri ri ucl r venin e dyes from interme Y I d ates prepa ed as illustra ed above was effected in 2: EXAMPLE 29 quaternary anhydro inner alt of Example 2, t condensation teacher! being formugxampk was condensed with 2-methy| 6-meth0xy .llililfififiii'fix .3 carboxyethyl-benzothiazolium iodide in accordance S with the procedure of ExarnpleZ to form a trinuclear l win 0 methine dye having the following formula:

"5g; 0:;5 is' 47CHEQ N =0 -l ll: H-/

I H5 :H JhHgCOOH YHCQHfiCeS I O= l 30 w N The ntermediateanhydro salt of Example H as l B; condensed with 2-methyl o-rnethoxy-3-carboxyethylhenzothiaz lium iodide in accordance with the procee ein Y, M, R, R and R signify the moieties shown dure of Example 2 to form a trinuclear methine dye i following Tablez. v having the formula:

TABLE 2 Example No. v M R R! R5 Rt 2 hy v -me oxy carh xy l'l 13 S S ethyl ethyl r H carboxyethyl M S Se ethy e hyl fimel o y carboxyethy l5 5 S ethyl t y fi methyl fi-me' hoxy d 16 S S e yl me hyl -meth y d l S S yl methyl H do.

18 S S ethyl allyl -methoxy do.

19 s s ethyl ally! do.

20 S S a ly! all?! o-me hoxy do.-

21 S S ally] allyl H do.

22 S S ethyl carbqxyethyl -methoxy do.

23 S. S phenyl ethyl fi-methoxy do.

24 O S ethyl ethyl firmethogy do.

Additiona trinuclear dyestuff ere similarly ere pared naf th r se ies. of examples from interm diate 1; s 1 quaternary anhydro saltsv by condensation in the. mang JJ 0011. ner a e ill rated, the r action eing formulated s 1 7 follows: N W m hm Y-.. ..o,=o:g s ou ,mooon F0 6 0 0580.113 0:; 7

l i The tnnuclear dyestuffs, as prepared 1n accordance x J with Examples 12 to 30, are excellent sensitizers for vfiog ems +3 EiflQQKiQElfl n atqsondystiveins lathflwxsisflsc- {1;}; 11 l trophotographic materials. [n.preparing such materials, =8 photoconductwe zinc oxide rs mrxed with a solution in i A a volatile orgamc solvent of a resm adapted to serve as N an insulating binder, and a solution of the trinuclear I. sensitizing dye in a compatible solvent such as methamethanol were added, and the mixture thoroughly agitated for 30 minutes. It was then coated on a paper base nol or ethanol is added. After thorough mixing, the s s mixture is coated on a paper base, preferably impregnated with a salt such as an alkali or alkaline earth f C=CH C metal halide, or a cationic resin, e.g., of the type de- I scribed in US. Pat. No. 3,011,918, to increase its elec- C 2H5 a trical conductivity. The following example illustrates preparation of an electrophotographic material in acand cordance with this procedure: 0 s

CH; S *W "an" 1O \C=CH-CH=C/ \(I3=CH-C/ 3 0: --N 0.09 g. each of 6 percent by weight xylene solutions 1 6 (M20003 of cobalt naphthenate and manganese naphthenate 2 4 3 were dissolved in 260 ml. of toluene. 91.8 g. of 50 per- 1 5 o a po yg yCl y et er 0 is-paray roxyp eny dimethylmethane, esterified with soyabean fatty acids im k: y ggg l b l pi and dimeri zed linseed fatty acids, and 18.2 g. of 67 perggl le g t s ti sn t ge tfgie ogr agiie Qd 6: 513 832:

ggg f gf a f i g fif ifig giii zmfiggf about 50 percent better thaifsai d cyanin dyes in resis- 454 g. of photoconductive zinc oxide (St. Joe Pc-331 tame t bleaching on q to light n p were then added, and the mixture milled until smooth. raged 111 roplfiotographic Z 1nc oxile coatiulgst.

20 m of the d e of Exam le 2, dissolved in 20 ml. of r p rposes 0 sensitizing zmc 0x1 e as a p o ocong y p ductor for electrophotography, the trinuclear dyes of this invention having atleast one carboxyalkyl group containing as a conductive increasing component, joined to a heterocyclic nitrogen atom are preferable,

polyvinyl-benzylamine hydrochloride, a d dri d, Th Variations which will be obvious to those skilled in coating amounted to 20 lbs. of solids per 3,000 sq. ft. the art can be made in the foregoing examples without of surface. As compared with papers prepared instead depart ng from the scope or spirit of the invention.

with cyanine dye sensitizers' having the following for- I claim mulas: l. A trmuclear methme dye having the formula:

C uHs ,mcoon 

1. A TRINUCLEAR METHINE DYE HAVING THE FORMULA: 